ok, i am not native speaker, so there is high chance i might have used wrong word (i wanted to use other one, but i couldnt get it even in slovak so i couldnt translate it), but lets see what we have here
you took definition of "prejudices" from third link in google, just so it suits your own definition of the word itself, in which they use word "unreasonable" in every single explanation
now lets see about other 2 links what they have to say wikipedia.org - Prejudice is an affective feeling towards a person or group member based solely on that person's group membership. dictionary.com - an unfavorable opinion or feeling formed beforehand or without knowledge, thought, or reason.
and lets see exactly this example - we meet canadian guy and we find out he is french canadian. now considering my previous experience with french canadians, i formed opinion towards that group of people, and eventho i dont have knowledge about this guy, i still connected my opinion about the group he comes from with him. what i did there - without knowledge of the guy, i made unfavorable feeling towards the guy.
honestly, i dont even see other possible way how to use this word, not saying i am correct, thats how i understand it.
and just so i can be ass to someone who actually lives in country which main language is english, you should know that term "french canadian" doesnt refer to race, so thinking what i say here is "racial prejudgments" isnt correct ps: i forgot we are in 2k18 and ppl are pussies about being offended and think that offending people is not socially acceptable, i see you prefer people judging silently rather than saying things to their faces, cool, cool